1. Field of the Invention
This invention relates to an information recording method and an information recording system for adding new record information to old record information already recorded on a record medium or replacing the old record information with new record information and more particularly to an information recording method and an information recording system for adding new record information to old record information or replacing old record information with new record information while executing coding of MPEG (Moving Picture Experts Group), etc., for example, and executing the same coding for old record information already recorded on a record medium.
2. Description of the Related Art
Hitherto, the coding technology of MPEG has been available as a highly efficient compression coding technology for an image.
The coding technology of MPEG is a technology of making it possible to highly efficiently compress image information which essentially reaches an enormous information amount by executing variable-length coding of difference information between an image to be coded and a reference image preceding the image in time sequence and a motion vector, which refers to a vector indicating the direction and amount of image motion if some image motion exists between the reference image and the image to be coded, in macro block (square pixel block containing 16xc3x9716 pixels) units and transmitting or recording the result.
Since variable-length coding is executed as described above in the coding technology of MPEG, the post-compressed and coded images, which will be hereinafter referred to as pictures, differ in data amount.
Therefore, the encoder for executing the coding sets the amount of data to be coded while simulating the stored data amount in reproduction buffer memory (buffer memory for temporarily storing decoded image and adjusting the output timing, etc.,) in a decoder at the coding time so that when coded image is decompressed and decoded in the decoder, an overflow or an underflow does rot occur in the reproduction buffer memory in the decoder (if an overflow occurs, an undecoded image occurs; if an underflow occurs, decoded image discontinues), whereby an overflow or an underflow is avoided.
By the way, according to the highly efficient compression coding technology described above in the related art, to start recording a new image on a record medium, it is necessary to initialize all of various coding parameters involved in the coding (parameters to be set at the coding time, such as VBV (Video Buffering Verifier) delay, picture size, temporary reference, and picture coding type).
[Means for Solving the Problem]
However, according to the related art, for example, to maintain scene transitions in recording for once recording an image on a record medium and then recording a new image relevant to the previously recorded image (for example, continuous with the previous image), the above-mentioned coding parameters are all initialized each time recording a new image is started, thus continuity of the coding parameters at the scene transition part is impaired. Resultantly, continuity is not set between the simulation result of the buffer memory in the decoder executed by the encoder when the last part of the previous image is coded and recorded and the simulation result of the buffer memory executed by the encoder when the first part of the new image is coded and recorded.
Thus, the stored data amount in the buffer memory in the decoder as the simulation result containing the parts before and after the scene transition part, performed by the encoder differs from the actual stored data amount in the buffer memory in the decoder for reproducing the new image as a sequence of images with respect to the previous image together with the previous image and the continuity on the MPEG standard is impaired in the part corresponding to the scene transition part. Resultantly, when the image is reproduced, an overflow or an underflow occurs in the buffer memory in the decoder after the scene transition part, in which case irregularity may be caused in the image as a result.
It is therefore an object of the invention to provide an information recording method and an information recording system capable of coding and recording a new image relevant to a previously coded and recorded old image in a similar manner and when both the old and new images are reproduced continuously, enabling the old and new images to be reproduced smoothly without impairing the continuity of the reproduced images at the scene transition part.
To the end, according to a first aspect of the invention, there is provided an information recording method for coding and recording new record information to be recorded on a record medium such as DVD-R/W on which old record information is already coded and recorded, the information recording method comprising the acquisition step of acquiring an old coding parameter of a coding parameter used to code the old record information, the setting step of setting a new coding parameter of a coding parameter used to code the new record information so as to continue with the acquired old coding parameter, and the recording step of coding the new record information using the setup new coding parameter and recording the new record information on the record medium.
The old coding parameter is acquired and the new coding parameter is set so as to continue with the old coding parameter, then the new record information is recorded while coding is executed. Thus, to reproduce the old record information and the new record information, the old record information and the new record information coded based on the continuous coding parameters are reproduced; the old record information and the new record information can be reproduced without becoming discontinuous therebetween.
To the end, in a second aspect of the invention, in the information recording method as set forth in the first asspect of the invention, the new record information is new record information to be recorded on the record medium so as to continue with the old record information, the acquisition step comprises the storage step of storing the old coding parameter corresponding at the termination of recording the old record information in storage means, and the read and acquisition step of reading and acquiring the stored old record information when the new record information is recorded, wherein the setting step sets the read old coding parameter as a new coding parameter, and the recording step starts coding the new record information using the setup new coding parameter and stores the new coding parameter corresponding at the termination of recording the new record information in the storage means in place of the old coding parameter.
At the termination of recording the old record information, the corresponding old coding parameter is read out and acquired from the storage means and is used as new coding parameter to start coding the new record information. Further, at the termination of recording the new record information, the corresponding new coding parameter is stored in the storage means in place of the old coding parameter. Thus, even when the new record information is the record information to be recorded continuing with the old record information, the continuity of the coding parameters is provided reliably and the new record information can be recorded.
To the end, in a third aspect of the invention, in the information recording method as set forth in the first aspect of the invention, the new record information is new record information to be recorded on the record medium so as to update a part of the old record information, the acquisition step comprises the read step of reading adjacent old record information of the old record information recorded on the record medium adjacent to the top of the area of the record medium in which the old record information of the part is recorded from the record medium, and the calculation step of calculating the old coding parameter corresponding at the termination of recording the adjacent old record information based on the read adjacent old record information.
The old record information recorded in the area adjacent to the top of the area in which new record information is to be recorded is read and old coding parameter is calculated based on the read old record information. Further, a new coding parameter is set so as to continue with the calculated old coding parameter and the new record information is coded. Thus, even when the new record information is the new record information to be recorded so as to update a part of the old record information, the continuity of the coding parameters is provided reliably and the new record information can be recorded.
To the end, in a fourth aspect of the invention, in the information recording method as set forth in any one of the first to third aspects, coding of the old record information and coding of the new record information are compression coding executed based on MPEG, and the coding parameters include at least coding parameters of VBV delay, picture size, temporary reference, picture coding type, SCR, PTS, and DTS.
To code the old record information and the new record information in MPEG, a new coding parameter is set so that the coding parameters of VBV delay, picture size, temporary reference, picture coding type, SCP, PTS, and DTS at least are made to continue. Thus, the continuity of coding between the old record information and the new record information can be maintained reliably, and the old record information and the new record information can also be reproduced while the continuity is maintained between the old record information and the new record information.
To the end, according to a fifth aspect of the invention, there is provided an information recording system for coding and recording new record information to be recorded on a record medium such as DVD-R/W on which old record information is already coded and recorded, the information recording system comprising acquisition means such as a CPU for acquiring an old coding parameter of a coding parameter used to code the old record information, setting means such as a CPU for setting a new coding parameter of a coding parameter used to code the new record information so as to continue with the old coding parameter, and recording means such as a pickup for coding the new record information using the setup new coding parameter and recording the new record information on the record medium.
The old coding parameter is acquired and the new coding parameter is set so as to continue with the old coding parameter, then the new record information is recorded while coding is executed. Thus, to reproduce the old record information and the new record information, the old record information and the new record information coded based on the continuous coding parameters are reproduced; the old record information and the new record information can be reproduced without becoming discontinuous therebetween.
To the end, in a sixth aspect of the invention, in the information recording system as set forth in the fifth aspect, the new record information is new record information to be recorded on the record medium so as to continue with the old record information, the acquisition means comprises storage means such as memory, storage control means such as a CPU for storing the old coding parameter corresponding at the termination of recording the old record information in the storage means, and read and acquisition means such as a CPU for reading and acquiring the stored old record information when the new record information is recorded, the setting means sets the read old coding parameter as a new coding parameter, and the recording means starts coding the new record information using the setup new coding parameter and stores the new coding parameter corresponding at the termination of recording the new record information in the storage means in place of the old coding parameter.
At the termination of recording the old record information, the corresponding old coding parameter is read out and acquired from the storage means and is used as new coding parameter to start coding the new record information. Further, at the termination of recording the new record information, the corresponding new coding parameter is stored in the storage means in place of the old coding parameter. Thus, even when the new record information is the record information to be recorded continuing with the old record information, the continuity of the coding parameters is provided reliably and the new record information can be recorded.
To the end, in a seventh aspect of the invention, in the information recording system as set forth in the fifth aspect, the new record information is new record information to be recorded on the record medium so as to update a part of the old record information, the acquisition means comprises read means such as a pickup for reading adjacent old record information of the old record information recorded on the record medium adjacent to the top of the area of the record medium in which the old record information of the part is recorded from the record medium, and calculation means such as a CPU for calculating the old coding parameter corresponding at the termination of recording the adjacent old record information based on the read adjacent old record information
The old record information recorded in the area adjacent to the top of the area in which new record information is to be recorded is read and old coding parameter is calculated based on the read old record information. Further, a new coding parameter is set so as to continue with the calculated old coding parameter and the new record information is coded. Thus, even when the new record information is the new record information to be recorded so as to update a part of the old record information, the continuity of the coding parameters is provided reliably and the new record information can be recorded.
To the end, in an eighth aspect of the invention, in the information recording system as claimed in any of the fifth to seventh aspects, coding of the old record information and coding of the new record information are compression coding executed based on MPEG, and the coding parameters include at least coding parameters of VBV delay, picture size, temporary reference, picture coding type, SCR, PTS, and DTS.
To code the old record information and the new record information in MPEG, a new coding parameter is set so that the coding parameters of VBV delay, picture size, temporary reference, picture coding type, SCR, PTS, and DTS at least are made to continue. Thus, the continuity of coding between the old record information and the new record information can be maintained reliably, and the old record information and the new record information can also be reproduced while the continuity is maintained between the old record information and the new record information.